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The most common question I receive over the winter months related to winter wheat production is “How is the cold weather/warm weather/lack of snow impacting my winter wheat?” Unfortunately, there are no easy answers over the winter months as we typically have to wait until spring when winter wheat breaks dormancy and stand establishment is known.

However, there can be a few key factors during fall establishment and weather conditions over the winter months that can provide guidance in terms of assessing weather and its impact to Manitoba’s winter wheat prior to the crop actively resuming growth next spring.

First step: record crop condition prior to winter. The crop stage and health/vigour of the crop as it heads into winter will provide an indication if the crop has a high chance of surviving the winter with minimal winterkill or winter injury. Ideally plants should be at the 3 leaf to 1 tiller stage and have well-developed crown tissue (and of course established into adequate standing stubble to ensure snow catch). And remember, the stage of crop development in the fall influences not only winter survival, but also yield potential, crop competitiveness, maturity and the risk of infection with diseases such as rust and fusarium head blight.

Second step: note the weather after seeding and prior to winter. Cool conditions in the fall where plants grow for 4 to 5 weeks, followed by 4 to 8 weeks (October to November) of growth that allow plant to acclimate and vernalize, is the ideal situation (relates back to an optimum seeding date of the first couple weeks of September). Read more about cold acclimation and vernalization here: http://cropchatter.com/winter-wheat-survival-impacted-by-fall-management-decisions-the-weather/. Another key weather factor is open field conditions with little or no snow cover until freeze-up as this allows soil temperatures to gradually decline to freezing levels.

Third step: record any weather stresses over the winter months. In the fall, winter wheat producers can take all the necessary steps to set their crop up to survive winter with minimal winterkill or injury. However, it is often the winter/early spring weather in Manitoba that can impact winter survival. Producers should take notes of cold snaps (how long they lasted, when did they occur) and the snow cover during those events to gauge potential impact to their winter wheat crop.

Regardless of the amount of cold acclimation, we typically need to receive good snow cover to protect the crop from the sustained cold temperatures normally seen in January and February in Manitoba. The ideal situation would be a minimum of 4 inches of trapped snow cover through December to early March to buffer soil temperature changes and provide protection to the crown tissue.

Plant stage would be at the 3 to 4 leaf with 1 to 2 tillers, and well developed crown tissue.

Cool conditions in the fall, where plants would grow for 4-5 weeks, followed by 4-8 weeks (October to November) of growth that allowed plant to acclimate (harden off) and vernalize (giving the plant the signal to flower next spring).

A minimum of 4 inches of trapped snow cover through December to early March to buffer soil temperature changes and provide protection to the crown tissue.

What is cold acclimation and vernalization?

Cold Acclimation. The ability of the winter wheat plant to survive the winter often depends on its ability to withstand low temperatures. Under normal field conditions, eight to twelve weeks of growth is usually required for the full development of winter hardiness. The first four to five weeks is a period of active growth that takes place when average daily soil temperatures at a depth of two inches (5 cm) are above 9°C. Both the cold acclimation process and winter survival require energy and this period of warm temperature allows for the establishment of healthy vigorous plants. Plants with well developed crowns before freeze-up are most desirable. However, plants that enter the winter with two to three leaves are usually not seriously disadvantaged.

Cold acclimation of winter wheat plants begins once fall temperatures drop below 9°C. In the field, four to eight weeks at temperatures below 9°C is usually required to fully cold harden plants. However, regardless of the amount of cold acclimation, the wheat plant must receive insulating snow cover to survive the cold prairie winters.

Vernalization. During the period of cold acclimation, the low temperatures also initiate in the plant a physiological response called vernalization. During vernalization, the plant converts from vegetative to reproductive growth and the reproductive structures are developed. Because of this vernalization requirement, winter wheat produces only leaves for both the main stem and tillers aboveground in the fall in preparation for winter. The growing point and buds of both the main stem and tillers remain belowground, insulated against the cold winter temperatures. Once vernalization requirements are met, the growing point differentiates and develops an embryonic head. At this time, wheat head size or total number of spikelets per head is determined. What is important to note here is neither seedling growth nor tillering is required for vernalization to occur. This process can begin in seeds as soon as they absorb water and swell. Hence, late planted wheat that has not emerged prior to winter should be adequately vernalized. Or in extreme conditions, vernalization may occur under cool spring conditions.

With canola coming off in Manitoba, now is the time of year where producers are making plans to seed winter wheat. There have been numerous posts on Crop Chatter regarding winter wheat production over the past year and I’ve summarized the most relevant ones to seeding below:

Another excellent source of information is the Western Winter Wheat Initiative website at: http://www.growwinterwheat.ca/. The Western Winter Wheat Initiative is a collaboration between Bayer Crop Science, The Mosaic Company Foundation, Richardson International, and Ducks Unlimited. It provides information and support in agronomy, products, and grain marketing to ensure winter wheat is a crop that is sustainable and profitable for farmers. So check it out!

Producers are encouraged to continue scouting their winter wheat and spring wheat fields as early detection is important. The good news is wheat stripe rust can be managed by timely fungicide applications. If the disease pressure, weather conditions and crop yield potential warrant application, foliar fungicides should be applied before the disease is well-established in the crop to provide maximum benefit. There are numerous products available for the control of stripe rust; please refer to the Guide to Field Crop Protection.

If rust infections are only noticed later, especially past the flowering stage, a fungicide is likely unwarranted as the yield effect will be minimal.

Soil temperatures in four winter wheat fields were measured throughout the 2014/15 winter. Plotting soil temperatures against various ‘hardiness” curves can provide an early indication if there is a concern for winter injury or winterkill. I had posted initial data (up to beginning of March – http://cropchatter.com/early-indicators-for-wheat-survival-in-2015/), and presented that data at the Winter Cereals Manitoba AGM middle of March.

However, the figure is now updated to include data up until middle of April when the weather stations were removed from the fields.

Since majority of winter wheat acres are considered “well-hardened” and soil temperatures didn’t reach levels that went below the “high hardiness’ curve, winterkill isn’t expected to be a large concern based solely on soil temperatures measured in these fields over the winter. However, since soil temperatures at one location did dip below the “mid hardiness’ curve, or at some locations got close to that curve, some areas within fields may be impacted where there was perhaps minimal snow cover due to lack of stubble, etc. Each field should still be scouted and assessed as growth resumes in earnest over the next few weeks.

Note: You will notice the hardening curves end beginning of April as I don’t have data to continue the curve to May 1st. However, imagine a curve for each line continuing upward until approximately the -2°C mark.

The ability of the winter wheat plant to survive the winter often depends on its ability to withstand low temperatures. Through the process of “cold acclimation” the plant acquires cold tolerance or winter hardiness. Factors that can impact the level of cold hardiness of the plant include weather, fertility, seeding date, and seeding depth. For the 2014/15 winter wheat crop, majority of acres would likely be considered “well-hardened”.

Since majority of winter wheat acres are considered “well-hardened” and soil temperatures didn’t reach levels that went below the “high hardiness’ curve, winterkill isn’t expected to be a large concern. However, since soil temperatures at one location did dip below the “mid hardiness’ curve, or at some locations got close to that curve, some areas within fields may be impacted.

Early Assessment of Growth. From early reports of producers and agronomists bringing in winter wheat plants from the field or conducting the ‘bag test’ to assess winter survival, regrowth has been noted which is also good news. Continued scouting is encouraged though as fields start to break dormancy and growth resumes with earnest.

So between early assessments and the measured soil temperatures, winter wheat survival looks promising to date. Keep in mind these early indicators shouldn’t stop you from assessing your own winter wheat fields though. As well, the weather in the coming weeks will play a large role in telling the final story of winter wheat’s survival.

Spring is right around the corner…hopefully! It is that time of year where producers start thinking about their winter wheat crop and how it survived our Manitoba winter. There are 3 common ways to assess winter survival.

1. Sod Extraction Method – A producer can extract several ‘sods’ from the field with a shovel. Warm up the sods inside while keeping the soil moist. In 5 to 7 days, assess the crowns for new root growth which indicates the plant has survived.

2. Bag Test Method – This method was developed by Ducks Unlimited in North Dakota and involves five easy steps:

1) Dig or chisel plants out of the soil without damaging the crown.

2) Rinse the soil off the crown and roots.

3) Using scissors, trim off the roots and leaves and all but one inch of the stem above the crown.

4) Put the crowns in a Ziploc bag and puff some air into it before sealing.

5) Keep at room temperature and observe every 2 days. Repeat the rinsing and air every 2 days.

3. The Wait for Spring Growth Method – This method requires producers wait until the crop breaks dormancy and new root growth commences out in the field; this could take until mid-May in some years depending on spring weather conditions. This method does still require producers dig up plants within the field as brown, dried leaves do not necessarily indicate winter injury, and green overwintering leaves are not a sure sign that the crop has survived. To properly assess, dig up some plants, rinse the roots with water and examine the crown for the development of new white roots. If new roots are developing, and the crown appears white and healthy, the plant is likely in good condition.

Regardless of method used to assess winter survival, producers should still scout their winter wheat fields to determine plant stands. It has occurred where plants will green up and then slowly go ‘backwards’ and eventually die; there are enough nutrients in the crown to allow the plants to green up, but if winter injury occurred, it can cause vascular damage so that the nutrients that are left cannot move, or root rot diseases can move in and kill the plants. So don’t scout the field once and assume all is okay.

Additional information on winter wheat production is available on Crop Chatter:

The cold temperatures arrived quickly in Manitoba. And with those cold temperatures and the minimal snow cover, I received my first “how is the winter wheat doing with the recent cold snap?” question of the 2014/15 winter wheat crop year!

The quick answer is the cold snap likely hasn’t had much of an impact. In looking at the soil temperatures in the four winter wheat fields we have real-time monitoring in (see the CropChatter post at http://cropchatter.com/real-time-regional-winter-wheat-in-field-soil-temperature-monitoring/), soil temperatures have dipped around the minus 5 degree Celsius mark. Fortunately, winter wheat is at its hardiness in November and December (see below Figure). Also, in the late fall (prior to Dec. 20), the soil has a large heat capacity and decreases in soil temperature lag considerably behind decreases in air temperature. Therefore, the probability of the recent cold snap damaging the winter wheat crop is very low.

Source: Winter Cereal Production, University of Saskatchewan

We also need to remember that many winter wheat acres were seeded under “optimal” conditions, including before or at recommended seeding dates, into fields with standing stubble, and into good soil moisture helping the crop emerge quickly and uniformly (reaching the recommended stage of 3 leaf to 1 tiller prior to snow fall). These best management practices lend themselves to a winter wheat crop that is well-hardened.

However, even with those positives, we still need good snow cover starting mid-December to protect the crop from the sustained cold temperatures we typically see in January and February in Manitoba.

Despite the delayed harvest of 2014, Manitoba producers did seed a limited acreage of winter wheat. It is estimated seeded acres are at or below 200,000, which is down from what was seeded in Fall 2013 and 2012 (see Table 1).

Table 1: Historical Acres of Winter Wheat Seeded in Manitoba

Source: MASC Seeded Acreage Reports 2009-2014.

Fall Establishment. The good news is much of that seeding occurred under “optimal” conditions – before or at recommended seeding dates, into fields with standing stubble, and into good soil moisture. The winter wheat crop emerged quickly and uniformly, reaching the recommended stage of 3 leaf to 1 tiller prior to snow fall.

The stage of crop development in the fall is important as it not only influences winter survival, but it can also impact yield potential, crop competiveness and maturity. However, winter survival is also influenced by fall management practices, including variety selection, seeding date and depth, fertilizer placement and stubble conditions.

Take Notes Now & Over the Winter. Manitoba producers have done their part to ensure their crop reaches maximum winter hardiness. Now is where we hope for good snow cover and moderate winter temperatures so the 2014/15 winter wheat crop can overwinter and emerge in spring in excellent condition! To help you with spring assessment of winter survival and crop life, record the following over the winter:

crop’s condition such as crop stage and stand prior to snow cover. Also note well acclimated plants will hold leaves close to the ground.

winter stresses such as cold snaps, when they occurred and their duration,

length and timing of snow cover. For winter survival, February/March snow cover is the best.

Lionel Kaskiw, Farm Production Advisor based out of Souris submitted this photo, taken by fellow Farm Production Advisor Elmer Kaskiw (Shoal Lake), of spring germinating winter wheat. According to Lionel, this is a common site in winter wheat fields across the Southwest Region as dry conditions at seeding didn’t allow for germination to occur last fall.

There are a few key points to keep in mind when managing a crop that only germinated in the spring. The crop will not be as competitive so early weed control and early nitrogen fertilizer application will be very important. Maturity may also be delayed so producers are encouraged to scout for disease through the growing season, including rust and fusarium head blight.

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Reference material

Diseases: New clubroot cases have been confirmed in the Rural Municipalities of Lorne and Dufferin. Insects: Scouting for bertha armyworm continues with some reports of insecticide applications. Spider mites being noticed in some soybean fields. Grasshopper populations are variable. For full report see Insect & Disease Report – August 1, 2018

Crops are advancing rapidly with the warm and dry conditions. Rain is needed in most areas to sustain crops and replenish soil moisture. Harvested has started in winter cereals, barley, and peas. Swathing or pre-harvest applications have started in early seeded spring cereals and canola. Fist cut hay is nearing completion; yields are below normal. […]

Diseases: The second case of clubroot in canola this year has been reported. Disease surveys in soybean and wheat are ongoing and disease levels are low overall. Insects: Overall insect concerns in field crops are relatively low. There are still some areas where grasshopper levels are being watched. Spider mite levels are being monitored in some soybean fields in […]

Disease – Goss’s wilt was observed near St. Claude. Insects – Grasshopper populations are being monitored in and around the edges of some fields. Armyworms have been noticed in some cereal fields in the Central and Eastern regions. No soybean aphids have been reported yet. For more details and information see http://www.gov.mb.ca/agriculture/crops/seasonal-reports/manitoba-insect-and-disease-update-2018-07-11.html

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Favourable weather and field conditions have allowed seeding operations to begin, with a provincial estimate of <5% of the 2017 crop seeded. For the full crop report, see on-line at http://www.gov.mb.ca/agriculture/crops/seasonal-reports/crop-report-archive/crop-report-2017-05-01.html

The Guide to Crop Protection provides information on the use of herbicides, fungicides and insecticides for control of weeds, plant diseases and insects. This publication is only a guide. Always refer to the product label for application details and precautions. It is available: online at https://www.gov.mb.ca/agriculture/crops/guides-and-publications/#gfcp. Individual sections on Weed Control, Plant Disease Control and Insect […]

Did you know you can view the 2017 edition of Seed Manitoba, as well as past editions, on www.seedmb.ca? Well, you can! Flip-view digital editions of the current guide (2017), as well as the six most recent editions, are available at http://www.seedmb.ca/digital-edition/. Also, full PDF versions are available at http://www.seedmb.ca/digital-edition/pdf-editions-and-separate-section-pdfs/ where you can download the entire […]

http://www.gov.mb.ca/agriculture/crops/plant-diseases/clubroot-distribution-in-manitoba.html Map shows positive clubroot findings by Rural Municipality, discovered through laboratory testing for presence of clubroot spores in soil and/or positive confirmation of clubroot symptomatic plants. Testing was done from 2009-2014 and is still considered limited. Positive findings have been at low spore concentrations and sporadic throughout the province. As more fields are sampled, the map will be updated. As less than […]